Heater assembly with expansion tank



Jan. 4, 1955 E. H. H AUGEN 2,698,739

HEATER ASSEMBLY WITH EXPANSION TANK Filed May 8, 1950 IN VEN TOR.

ram/v0 hi HAUGEN BY A TTORNEYS mww HEATER ASSEMBLY WITH EXPANSION TANK Edmond H. Haugen, Birmingham,v Mich; assignor,

: mes'ne assignments, to Rockwell Spring'and Axle Com pany, Coraopolis, Pa.,- a corporation of Pennsylvania Application May 8, 1950, Serial No. 160,691

3 Claims. Cl. 257-203 This invention relates generally to hot water heating systems and more specifically to a novel expansion tank and domestic hot water heater assembly.

It is the major object of this invention to provide in a closed hot water heating system, a novel expansion tank having at least a portion of its walls submerged in a storage tank for domestic hot water for heating the water in the storage tank.

A further object of this invention is to provide in a closed hot water heating system an elongated expansion tank having communicating air and water spaces, and a domestic hot water storage tank surrounding the water space of the expansion tank.

Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawing wherein the figure illustrates the boiler, expansion tank and hot water storage tank in the system, with the tank assembly in section to show the common wall construction of the preferred embodiment.

A boiler 11, which may be of any conventional type such as that disclosed in United States Letters Patent No. 2,491,517 issued on December 20, 1949 to M. A. Powers et al., has its hot water space connected by a supply main 12 and a return main 13 to radiators or other heat dissipating devices (not shown). A pump is provided in the system for circulating the boiler water therethrough.

The boiler hot water space is also connected by a conduit 14 and a return conduit 15 to an elongated vertically disposed cylindrical tank shell 16. The upper end of conduit 14 is connected by a horizontal conduit to the upper end of a relatively short pipe 17 that projects through the top wall 18 of tank 16, a water tight mounting and fitting being provided at 19. Wall 18 is an annular metal plate welded along its outer periphery to the inner wall of tank 16.

A safety valve 21 is provided, preferably in conduit 20, for discharging upon predetermined pressure in tank 16. Within tank 16, pipe 17 projects downwardly through an air space 22 and into a water space 23, the lower open end of pipe 17 being beneath the surface of the water.

The bottom wall 24 of tank 16 is an annular plate having its outer periphery welded to the inner wall of tank 16 and carrying a fitting 25 providing a water tight joint with conduit 15. Thus hot water from the boiler space rising through conduit 14 discharges through pipe 17 into expansion tank 16 and return conduit 15 completes circulation to the boiler. The water space 23 occupies the major part of the volume of tank 16, the size of air space 22 being that needed to accommodate expansion in volume of all of the hot water in the disclosed closed hot water system which includes the boiler, the radiator and the expansion tank. When the system is initially filled with water pumped through the boiler, tank 16 is filled with water up to the level of the bottom of pipe 17, air being displaced through conduit 15. After the water level in tank--16 covers the lower end of pipe 17, air is trapped in the upper air space portion of the tank and compressed somewhat to permit and maintain the illustrated water level in the tank. When water in the system expands in heating it further compresses the air in space 22.

The size of the expansion space at 22 may be varied to suit the needs of the system by lengthening or shortening the pipe 17 within tank 16. It will also be appreciated that the relative diameters of the air space and water space portions of tank 16 may be varied to suit conditions,

. 1: to be substantial extensions of each other.

.1 having no conduit fittings.

2 V as by making the tankdiameter of the-air space, somewhat larger wherespace conditions limit the vertical heightof the tank. V

: Expansion tank 16 is surrounded over its major portion by a cylindrical shell 26 which with the, surrounded outer I wall of. tank 16 and upper and lower end walls 27 and 28 respectively provides a domestic hot water heating and:

storage tank indicated at 29.

Upper end wall 27 is upwardlyconvex and has a cylindrical peripheral. flange. 30 fitting withintshell 26 and welded to it. A conduit 31 for supplying hot water to taps and other domestic devices entersthe storage tank 29 through a suitable watertight fitting in wall 27.

Lower end wall 28 is also upwardly convex, being preferably of the same shape and size as wall 27 but The outer periphery of wall 28 is formed'with acylindrical flange 32 that fits .within and is welded to shell 26. The inner periphery of wall 28.

is welded to shell 16 opposite the juncture of end wall 24- with shell 16 so that externally walls 24 and 28 appear A cool water inlet conduit 33 enters the bottom of the storage tank just above wall 28.

I have thus provided a novel compact expansion and hot water heating and storage tank assembly wherein the inner wall of; the heating and storage tank also serves as the outer wall of the expansion tank, which affords optimum heat exchange. The relative lengths of the tanks are such that the heating and'storage tank surrounds only water space of the expansion tank, the latter being made relatively long for providing a large area of heat exchange surface, and the air space portion of the. expansion tank projects above the level of the surrounding heating and storage tank. This provides an external surface of the expansion tank that is relatively cool and may aid in condensing any steam in the system.

An important aspect of the invention that contributes greatly to its efficiency in operation is that the boiler water, which is always hotter than the water in tank 29 to be heated thereby, circulates through a column in water space 23 that is protectively shielded and insulated by the surrounding tank 29. In this manner the full benefit of the hottest water is realized in that all of the heat extracted from the boiler water goes to heat the water in tank 29 and no boiler water heat is directly lost to the surrounding atmosphere by radiation. There are heat losses at the outer surface of tank 29 but since the water in tank 29 is at a lower temperature than the boiler water the temperature gradient is relatively lower at the outer wall of tank 29 and hence the actual heat losses from the assembly of the invention are appreciably lower than in most prior art assemblies wherein the domestic hot water tank is surrounded by the tank containing hotter boiler water, the latter having its outer surface exposed for radiation losses.

Exchange of heat between the tanks is both rapid and efiicient, and the domestic and boiler hot waters are never intermixed. Systems of this type have been found to provide adequate domestic hot water for an average family. For example, in a system wherein the capacity of storage tank 29 is 35 gallons I employ an expansion tank shell 16 about 8 inches in diameter and a shell 26 of about 18 inches diameter. The height of shell 16 is about 56 inches and shell 26 is about 48 inches so that about 8 inches of shell 16 projects above the storage tank. These figures are understood to be illustrative and in no way limiting the invention.

The entire assembly is mounted on a floor as by a stand 34 having four or more legs 35 and an annular support surface 36 formed with an upturned rim 37. The tank assembly seats on the stand within rim 37 with the bottom edge of wall flange 32 resting on flat surface 36.

The convex end wall structure of the combination tank structure provides resistance to stresses encountered during heating and cooling of the parts. The entire apparatus is sturdy and inexpensive to manufacture, and the entire combination tank assembly may be fabricated and tested at the factory so that only pipe connections need be made at the installation point.

The invention may be embodied in other specific forms without departing from the spirit or essential characterl atented Jan. 4,

istics thereof. The present embodiment is therefore to be considered in all respects as illustrative and-notre-- strictive, the scope of the invention being indicated by the appended claims rather than'by the foregoing description, and all changes which'come withinthe'meaning and range of equivalency of the. claims aretherefore. intended to be.

end of the outer tank so as to provide anextensioriof theinner tank above the outer tank, means'forintroducing hot boiler system water into the upper end. of said inner tank, a boiler system Water return connection at the lower end of said inner tank, the extension of said inner tank above the outer tank providing an air space which serves as an expansion space for the boiler water system, and water supply and withdrawal conduits connected to said outer tank which serves as a source of domestic hot water.

2. For use with. a boiler having means for circulating water through a space heating system, means for providing and storing domestic hot water comprising two'concentric tanks having a common heat exchange wall at their lower regions, said wall projecting above thelupper end of the outer tank so as to provide an extension of the inner tank above the outer tank, means for introducing hot boiler system water into the upper end of said inner tank comprising a pipe projecting downwardly through and terminating within said inner tank below the Water level therein, a boiler system water return connection at the lower end of said inner tank, the extension of said inner tank above the outer tank providing an airspace above said lower end of the pipe which serves as an expansion space for the boiler water system, and water supply and withdrawal conduits connected to said outer tank which serves as a source of domestic hot water.

3. For use with a boiler having means for circulating water through a space heating system, means for providing and storing domestic hot water comprising two upright concentric tanks having a common heat exchange wall at their lower regions, said wall projecting above the upper end of the outer tank so as to provide an extension of the inner tank above the outer tank, a transverse top wall on said innertank extension, means for introducing hot boiler system water into the upper end of said inner tank comprising a connection for a boiler system water supply conduit insaid top wall of said inner tank extension, and a substantially verticalpipe removably secured to said top wall to serve as a continuation of said supply conduit and terminating below the Water level in said inner tank, a boiler system water. return connection at thellower end of said inner tank, the extension of said inner tank above the outer tank providing an air space above the lower end of said pipewhich serves as anexpansion space for the boiler water system, and water supply and withdrawal conduits connected to said outer tank which serves as a source of domestic hot water.

References Cited in the file of this patent UNITED STATES PATENTS 1,338,055 Wadley Apr. 27, 1920 1,862,065 Rowe June 7, 1932 1,922,509 Thurm Aug. 15, 1933 FOREIGN PATENTS 202,794 Switzerland May 1, 1939 

